On Really Bright Screens

They’re good for more than the movies

Michael Herf
2 min readJan 14, 2014


Dolby just announced their Dolby Vision project. To make movies look better, they’re testing incredibly bright screens—20,000 nits—making so much heat they have to use liquid cooling. Normal screens clock in at just 200-400 nits, so it’s quite a jump.

I’m sure the images look splendid, but that’s not why I’m excited.

In the process of evolving our software f.lux, I’ve been reading lots of the academic literature on circadian health.

One idea you’ll find a lot is that our workspaces and homes are too dark during the day and (as we’ve been saying for a few years now) they’re also too bright at night, as we scroll away on iPads in bed.

Just as a ballpark, if we could make lights about 5 times brighter during the day, and about 5 times dimmer at night, we’d have a profound impact on circadian health. Instead, our artificial lighting has picked the middle of the road, and it’s not a very good compromise.

Simply making everything darker at night, like f.lux does, helps only half of the circadian system. It’s essential, but it’s not enough.

If our bodies need more light during the day, how do we do that? You might think it doesn’t involve screens at all.

But in an office, the screen is vital. If you add a big skylight over someone’s workspace, they’ll yell at you and insist they can’t use the computer, and please won’t you cover up all the glare?

But if you imagine screens that were 10 or 100 times brighter, we could add skylights and extra windows to our workspaces without compromising contrast and visibility. If we did that, we would trigger this wonderful part of our biology that really for-sure knows it’s daytime, and we’d also keep our day synchronized to a 24 hour cycle. All this light would probably have some impact on mood disorders, seasonal ones of course, but the research suggests a range of other conditions too, including even cancer, diabetes, and ADHD.

The only problem has been finding bright-enough screens. Mobile devices have advanced this somewhat, making screens you can mostly read in sunlight (maybe double the brightness we had before). But we need more, 10x or 100, like Dolby Vision.

I am very excited about this news from Dolby, because what looks good for cinema could turn out to be good for our health, too.



Michael Herf

co-founder of f.lux, finding the connections between circadian rhythms, sleep, healthy buildings, and light. (Previously made Picasa.)